Input: add touchscreen driver for MELFAS MCS-5000 controller

The MELPAS MCS-5000 is the touchscreen controller. The overview of this
controller can see at the following website:

http://www.melfas.com/product/product01.asp?k_r=eng_



This driver is tested on s3c6410 NCP board and supports only the i2c
interface.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>